Question

I have integrated ffmpeg lib in my project and I can also get the information of media files. But now i have to play mp3 files using AudioTrack class in android using ffmpeg lib.

For this I have to pass byte buffer to AudioTrack but I dont know how to get byte buffer from ffmpeg and use it with AudioTrack. I also want to play file instantly without delay.

Here is my audio track code in java :

AudioTrack track;
bufferSize = AudioTrack.getMinBufferSize(44100,AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT)
track = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSize, mode);

//Play audio clip
track.play();

while(stream_is_over){
//Copy the decoded raw buffer from native code to "buffer" .....
............
track.write(buffer, 0, readBytes);
}

Can anyone please give me the working code to play mp3 files with audio track. I have searched a lot but haven’t find any correct answer.

Answer 1

I managed this by creating buffer of audio files and then playing it with AudioTrack class on the fly.
Now i’m trying to pause/stop the audio file cause stopping or pausing AudioTrack is not working.

Here is my code to pass byte buffer to my java class :

#include <assert.h>
#include <jni.h>
#include <string.h>
#include <android/log.h>

#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"

#define LOG_TAG "mylib"
#define LOGI(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
#define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)

#define AUDIO_INBUF_SIZE 20480
#define AUDIO_REFILL_THRESH 4096

void Java_ru_dzakhov_ffmpeg_test_MainActivity_createEngine(JNIEnv* env,
        jclass clazz) {
    avcodec_init();

    av_register_all();

}

jstring Java_ru_dzakhov_ffmpeg_test_MainActivity_loadFile(JNIEnv* env,
        jobject obj, jstring file, jbyteArray array) {
    {
        jboolean isfilenameCopy;
        const char * filename = (*env)->GetStringUTFChars(env, file,
                &isfilenameCopy);
        int audioStreamIndex;
        AVCodec *codec;
        AVCodecContext *c = NULL;
        AVFormatContext * pFormatCtx;
        AVCodecContext * aCodecCtx;
        int out_size, len, audioStream = -1, i, err;
        FILE *f, *outfile;
        uint8_t *outbuf;
        uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
        AVPacket avpkt;
        jclass cls = (*env)->GetObjectClass(env, obj);
        jmethodID play = (*env)->GetMethodID(env, cls, "playSound", "([BI)V"); //At the begining of your main function

        LOGE("source file name is %s", filename);

        avcodec_init();

        av_register_all();

        LOGE("Stage 1");
        /* get format somthing of source file to AVFormatContext */
        int lError;
        if ((lError = av_open_input_file(&pFormatCtx, filename, NULL, 0, NULL))
                != 0) {
            LOGE("Error open source file: %d", lError);
            exit(1);
        }
        if ((lError = av_find_stream_info(pFormatCtx)) < 0) {
            LOGE("Error find stream information: %d", lError);
            exit(1);
        }
        LOGE("Stage 1.5");
        LOGE("audio format: %s", pFormatCtx->iformat->name);
        LOGE("audio bitrate: %d", pFormatCtx->bit_rate);

        audioStreamIndex = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_AUDIO,
                -1, -1, &codec, 0);

        LOGE("audio codec: %s", codec->name);

        /* get codec somthing of audio stream to AVCodecContext */
        aCodecCtx = pFormatCtx->streams[audioStreamIndex]->codec;
        if (avcodec_open(aCodecCtx, codec) < 0) {
            LOGE("cannot open the audio codec!");
            exit(1);
        }

        printf("Audio decoding\n");
        LOGE("Stage 1.7");
        LOGE("S");
        codec = avcodec_find_decoder(aCodecCtx->codec_id);
        LOGE("Stage 1.8");
        if (!codec) {
            LOGE("codec not found\n");
            exit(1);
        }
        LOGE("Stage 2");
//              c= avcodec_alloc_context();
        LOGE("Stage 3");
        /* open it */
        if (avcodec_open(aCodecCtx, codec) < 0) {
            LOGE("could upper");
            fprintf(stderr, "could not open codec\n");
            LOGE("could not open codec");

        }
        LOGE("Stage 4");
        outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);

        f = fopen(filename, "rb");
        if (!f) {
            fprintf(stderr, "could not open %s\n", filename);
            LOGE("could not open");
            exit(1);
        }

        /* decode until eof */
        avpkt.data = inbuf;
        avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
        LOGE("Stage 5");

        while (avpkt.size > 0) {
//                  LOGE("Stage 6");
            out_size = (AVCODEC_MAX_AUDIO_FRAME_SIZE / 3) * 2;
            len = avcodec_decode_audio3(aCodecCtx, (int16_t *) outbuf,
                    &out_size, &avpkt);
            LOGE("data_size %d len %d", out_size, len);
            if (len < 0) {
                fprintf(stderr, "Error while decoding\n");
                LOGE("DECODING ERROR");
                LOGE("DECODING ERROR %d", len);
                exit(1);
            }
//                  LOGE("Stage 7");
            if (out_size > 0) {
                /* if a frame has been decoded, output it */
//                      LOGE("Stage 8");
                jbyte *bytes = (*env)->GetByteArrayElements(env, array, NULL);
                memcpy(bytes, outbuf, out_size); //
                (*env)->ReleaseByteArrayElements(env, array, bytes, 0);
                (*env)->CallVoidMethod(env, obj, play, array, out_size);
//                      LOGE("DECODING ERROR5");
            }
            LOGE("Stage 9");
            avpkt.size -= len;
            avpkt.data += len;
            if (avpkt.size < AUDIO_REFILL_THRESH) {
                /* Refill the input buffer, to avoid trying to decode
                 * incomplete frames. Instead of this, one could also use
                 * a parser, or use a proper container format through
                 * libavformat. */
                memmove(inbuf, avpkt.data, avpkt.size);
                avpkt.data = inbuf;
                len = fread(avpkt.data + avpkt.size, 1,
                        AUDIO_INBUF_SIZE - avpkt.size, f);
                if (len > 0)
                    avpkt.size += len;
            }
        }
        LOGE("Stage 12");
        fclose(f);
        free(outbuf);

        avcodec_close(c);
        av_free(c);

    }
}